I keep my camera keep in a spare bedroom with my computer, etc in our 100 year old house - only occasionally air conditioned. Room hits 80+ in the summer (air conditioning keep the temp to around 80-84).

I would rather the room be dry and slightly warm versus humid and cooler

Hey all I pit up a shelf under my stairs where I have a small room and space under the stairs.

in this area I already have my network/server room. In that I mean server/network gear full rack. This area is very warm.

I wanted to see what people thought about this space for storing my lenses and bodies when not in use.

I'm concerned that the lenses might dry out something

I live in a place where the temperature reaches 131 Fahrenheit in July and August (even the night temperature is above 98 degrees fahrenheit ... this is when I go on holiday and leave several of my lenses in the house without Air Conditioning ... when I come back from vacation I can feel the heat from the walls ... but nothing ever happened to my lenses for the last 6+ years I've been doing this ... so I'm pretty sure the heat from your server won't cause any problems.

I only had issues once with an IKEA Cupboard I used to store lenses in:

The backside touched a wall which changed temperature often form hot to cold and vice versa.Moisture condensated, fungus grew and by the time you see this coming through the thin backside of modern cupboards you have spores everywhere.

In general, reliability drops as temperature increases. Several things happen, lubricants can break down and leak into places where they don't belong, plastics outgas and harden its a statistical thing. The decrease in reliability does not mean 100% or even 10% will fail, but it does mean that a failure is more likely. That's why elevated temperature testing is done with multiple units over thousands of hours, and periodically stopped to look a effects.

Much more important is the effect of rapid changes in temperature. Taking a product from 150 degrees Celsius to minus 50 degrees literally tries to tear a product apart due to thermal expansion and contraction. Parts can wear out mechanically from the stresses. Canon does test their cameras with thermal cycling. Its a excellent test to find the weak spots in a design in short order, a few cycles will usually cause a failure. Once all the weak spots in the design are fixed, the life time of the product will be greatly improved.

I was involved with a aircraft jet engine that was tested that way. Electronic boxes that are installed into a aircraft or space vehicle receive the same treatment.

The aircraft engine was run full thrust on the ground 24/7, stopping once a week for routine maintenance. The titanium in the engine turned blue from the heat, which was far above max operating temperature. Every time something broke, it was redesigned, or some sort of protection from the heat added. The best wiring insulation available cracked at far above its rated temperature, so heat deflecting shields were added. (the wire had max current going thru it) The concern for reliability was taken to extremes, and it paid off in super low failure rates.